Rescue of Neuronal Cell Death by ER-stress protein overexpression

ORP150是一种定位于内质网（ER）的新型应激蛋白。为了研究ORP150在延迟性神经元细胞死亡中的作用，我们检测了其在沙鼠脑缺血损伤后的表达。颈总动脉闭塞后，在CA1区观察到ORP150抗原及其转录本的表达，并通过预处理增强了这种表达。在培养的神经元中，暴露于缺氧或谷氨酸均可诱导ORP150的表达，并且在用thapsigargin或breferdina处理培养时也观察到这一点，表明谷氨酸和缺氧均可引起内质网应激（ER stress）。无论是环己亚胺处理，还是携带ORP150反义结构的腺病毒感染，神经元都更容易受到这些应激的影响。相反，腺病毒过表达ORP150抑制了神经元细胞的死亡，并伴随着谷氨酸诱导的Ca2+水平升高和蛋白水解活性的抑制。此外，携带ORP150感觉结构的腺病毒在CA1神经元中过表达ORP150可抑制缺血后延迟的神经元细胞死亡。这些数据表明ORP150可能作为一种细胞内装置，参与缺血耐受的保护反应。多巴胺能神经元的选择性丧失是帕金森病的最终共同途径。我们通过引入两个模型来讨论内质网应激在SNpc神经元细胞死亡中的作用。小鼠黑质部（SNpc）的pael受体上调可引起内质网（ER）应激，导致酪氨酸羟化酶减少和多巴胺能神经元死亡。在缺乏泛素蛋白连接酶Parkin和ER伴侣ORP150的小鼠中，多巴胺能神经元的死亡增加，表明ER应激在多巴胺能神经元易感性中的作用得到了强调，这表明Parkin功能障碍导致ER应激介导的神经元细胞死亡。相反，转基因大鼠过表达巨噬蛋白（Tg meg），一种新发现的丝氨酸蛋白酶抑制剂（serpin），显示出神经元内周期性酸希夫（PAS）阳性包涵体，分布在大脑皮层、海马CA1和黑质的深层。SNpc多巴胺神经元内质网应激增强，并伴有神经元活力和运动协调性的丧失。在这两个次区域，pas阳性包涵体也呈megsin阳性。这些数据表明，内质网应激增强会导致一组神经元群体的选择性易感性。少

ORP150 is a novel stress protein localized in the endoplasmic reticulum (ER). To investigate the role of ORP150 in delayed neuronal cell death, we have examined its expression in the gerbil brain after the ischemic insult. The expression of ORP150 antigen, as well as its transcripts, was observed in the CA1 region after the occlusion of the common carotid artery, and this was enhanced by the preconditioning. In cultured neurons, exposure to either hypoxia or glutamate induced the expression of ORP150, and this was also observed by treating the culture with either thapsigargin or breferdin-A, indicating that both glutamate and hypoxia can cause stress in the ER (ER stress). Neurons became more vulnerable to these stresses following treatment of either cycloheximide or the infection with an adenovirus carrying ORP150 antisense structure, In contrast, the overexpression of ORP150 by adenovirus suppressed the neuronal cell death, and this was accompanied by the suppression of the Ca2+ elev … More ation and proteolytic activity induced by glutamate. Further, overexpression of ORP150 in CA1 neurons by the adenovirus carrying ORP150-sense structure suppressed delayed neuronal cell death after ischemia. These date suggest a possible function of ORP150 as an intracellular apparatus, which participates in a protective response in ischemic tolerance.Selective loss of dopaminergic neurons is the final common pathway in Parkinson's disease. We discuss the role of ER-stress in neuronal cell death in SNpc by introducing two models. Upregulation of Pael-Receptor in the substantia nigra pars (SNpc) of mice induces endoplasmic reticulum (ER) stress leading to a decrease in tyrosine hydroxylase and death of dopaminergic neurons. The role of ER stress in dopaminergic neuronal vulnerability was highlighted by their enhanced death in mice deficient in the ubiquitin-protein ligase Parkin and the ER chaperone ORP150, suggesting parkin dysfunction result in ER-stress mediated neuronal cell death. Conversely, transgenic rats overexpressing megsin (Tg meg), a newly identified serine protease inhibitor (serpin), demonstrated intraneuronal periodic-acid Schiff (PAS) positive inclusions, which distributed throughout the deeper layers of cerebral cortex, hippocampal CA1, and substantia nigrta. Enhanced ER stress was observed in dopamine neurons in SNpc, accompanied with loss of neuronal viability and motor coordination. In both subregions, PAS-positive inclusions were also positive with megsin. These data suggest that enhanced ER stress causes selective vulnerability in a set of neuronal populations. Less